I have a developing issue with the starter motor on our 78 Corvette.

Back in the late 90’s I experienced the classic “hot start” situation – switching off the car and trying to start within 3-10 minutes meant that turning the key resulted in nothing, just a click. Once the starter had cooled off (after abut 15 minutes) it would start. That was cured by a starter re-build, which included a new solenoid.

However, in recent week I have noticed a slightly different behaviour. The car starts fine from cold. But, on occasions, after being switched off for about 5 minutes (just enough time to buy fuel for example), when I start the car the starter is “lazy”. By that I mean it is reluctant to turn over immediately, then does so very slowly, as in a dead or dying battery. Thankfully, it has always started up to now! When cold however, or if left for longer period, like half a day at an event, it starts normally.

The battery was fitted in January 2014, so is now a little over 4 years old. I’ve checked the various earth (ground) connections and all seem tight and clean.

So, does this sound like another starter re-build is necessary? Or, is it better to replace?

What is the situation with “shims” for the starter? I have read that this is a necessary process, something I avoided with a re-build of course.

As the car is an auto, I don’t want to get caught out somewhere!

Any thoughts advice please?

 

You could have any of numerous problems. Take your battery to some place to have it load tested. 4 years may be pushing it if you have hard start problems. Possibly the starter is getting too hot from manifold temps. Is the metal heat shield in place?
I prefer the high torque mini starters as they don"t seem to suffer from exhaust manifold heat as bad. As far as shims go, there are a mumber of ways to check. All are listed on the net if you do a search.
Good luck!

 

your shims do nothing but adjust how your starter gear meshes with the flywheel teeth.

plan on your battery losing 10% of its cranking amp capacity per year. so you have lost about 40% with a 4 year old battery. you can play around all you want with your connections and a new expensive high torque starter, but a nice new highest amp battery you can find will solve your problem. a hot engine, and a hot starter just takes more amps to crank than a cold one does. an older battery does not have that capacity it did 4 years ago.

 

I just went through the battery thing. Slow cranking when cold and some vary hard starting when hot. I was thinking that my oil was too heavy for cold starts and I need to to get a heat blanket for the starter to help with hot starting. Maybe a battery tender with a repair cycle!
No I bought a new battery, Autozone said that old battery was built in 7/2011 and I bought it in May 2012.
Now there are no starting problems!

 

Any oxidising in starter circuit can cause intermittent problems when hot. Not enough amps getting to your starter and when heat soaked it runs lazy and eventually not all. Symptoms can look very similar to a bad battery.

Clean battery posts and battery cable connectors (renew them if they are removable), clean connections in the starter too and all possible ground points you can find. Changing new battery and ground cables every few decades helps too as the cables can oxidise under the cover too.

Its a good idea also to clean alternator connections at the alternator and the power distribution point where it connects on the other end. It makes sure the car and the battery get good amps while driving.

Battery can be tested with a simple battery load tester. It will draw hundreds of amps in 10 seconds and tells you if the battery is ok. It can be a good idea to recharge the battery with a separate charger before reinstalling to the car so the alternator doesn't overheat charging a partially/fully depleted battery.

 

100% agree, every thing you speak of points to a weak battery, , I just went through the same thing,, i had the starter out, tested at the re-builders and they told me keep original starter, it is already t h e best heavy duty starter I could have,,, ( mini and gear reduction starters have a purpose, but with a good electrical system, you don't need one, IMHO ) , alternator tested perfect also, , I, like many people, fail to go with the easy fix first,,,

 

Thanks Toni. I guess I'm beginning to think along these lines, and a friend has had similar issues which were traced to a rather grubby solenoid interior! I've been through and replaced some of the cables already, but I'll be giving everything a good going over next week.

Getting things like battery load-tests done is not quite so simple out here in rural France, but as the starter spins over happily when the car is cold, or even warm usually, I'm not inclined towards the battery being the guilty party just yet. I've always got at least 7+ years out of the batteries on the Corvette in the past, so I'm hoping for a few more yet! But I've noted your comments on re-charging after a load test!

 

See if you can jumper from the battery to the solenoid terminal on the starter. I've run a long test wire from the battery or jumper from the battery terminal on the starter to test.

If you can jumper to the solenoid terminal and the starter works fine it's not the battery. Solenoids can get weak with age and heat and take more current. Sometimes the start contact on the ignition switch can't supply the required current.

I now always on any older GM starter use the ignition to starter solenoid wire to energize a relay. The relay then connects the starter battery connection to the solenoid terminal when energized. This insures max current on the solenoid.

 

Intersting info. Have you got a simple wiring diagram you could maybe PM me, someone who is most definitely not of an electrical engineering type!

I see that you are in the home of Carrs. If that Lotto win came in I always thought I'd let them do a "restomod" on the old '78 - nothing much changed outside, but all new underneath... Well, you have to dream!

 

Its good to have a load tester in your garage handy whenever you experience problems. Check fleabay.fr or .co.uk, there is loads of them and prices are cheap like 20-40 euros. Even the simplest one with analog gauge will take the guessing out of the game.

More expensive ones can also measure cold crank amps etc. nifty information which can come handy at some point.

Here in rural Finland every farmer and local small garage has one. I am sure its not difficult to find one locally if you don't want your own.

 

Stephen,

Sorry don't have a diagram.

If you can lift the car you find the starter has 3 terminals. The big terminal is where the + battery cable connects to the starter and joins with additional wires that power the various circuits. Most have a fusible link on this terminal.

There is a terminal on the solenoid labeled I which is ignition and is not used in vettes that run HEI so no connection.

There is another terminal on the solenoid labeled S which is start and is the connection from the ignition switch and is energized when in the start position. This is the one I run direct battery power to through a small relay. The wire I take off the S terminal is then used to energize the relay.

To test mine I connected an extra wire to the battery connection of the starter and an extra wire to the S terminal. I ran these up to a momentary push button switch. When the starter acted up I opened the hood and hit the switch (ignition switch in on position). My car always started right up so I then wired in a relay to replace the momentary test switch.

 

Dave, thanks for that. I'll be working with the car on axle stands, but I can at least get underneath! Won't be able to get to it until next week now though.

I'll have a good look at the situation and if I'm really brave may go with the relay system! Electrics are all a bit scary for me!